1. Field of the Invention
The present invention relates to a grinding apparatus and, more particularly, to an apparatus for grinding weld defects in a valve stem receiving area of a valve.
2. Prior Art
Devices for grinding, machining and resurfacing cylindrical objects are well known in the art. U.S. Pat. No. 4,246,728 to Leasher discloses a tool for treating an end of a tubular conduit having a rotatable body. U.S. Pat. No. 4,362,447 to Pekar et al discloses an adjustable face milling cutter carried on a turntable rotatable about a central axis to machine a circular path on an upper tubesheet surface. U.S. Pat. No. 4,388,782 to Rodgers et al discloses a grinder for preparing circular seats behind elliptical handholes of marine boilers. U.S. Pat. No. 4,513,542 by Wilger et al discloses a portable surfacing machine for boiler manholes. U.S. Pat. No. 4,534,135 to Wilger et al discloses a grinding machine for watertight hatch lugs. And U.S. Pat. No. 2,772,529 to Dutro discloses a cylinder block ridge grinder. In addition, U.S. Pat. No. 4,696,544 to Costella discloses a fiberscopic device for inspecting internal sections of construction.
In the manufacture of large valves, such as steam stop valves, parts must be welded together. When welding is involved, such as welding a ring type insert onto the internal flow surface of a steam stop valve, defects can appear. In order to provide a functional valve, these welding defects must be removed.
It is therefore an objective of the present invention to provide a grinding apparatus that can be placed into a valve through the valve stem area when the valve actuator, bonnet and valve gate are removed.
It is another objective of the present invention to provide a grinder that can grind the interior of conduits having a pneumatic motor for grinding and a fiberscopic device for visual observations of the grinding operation.
It is another objective of the present invention to provide an interior conduit grinder that can remove a local defect while the device is clamped in place or remove a continual defect on the 360 degree inner circumference of the weld between a ring type insert and a valve body when the grinder is not clamped in place.
It is another objective of the present invention to provide a grinder with a grinder motor that is adjustable for various depths of cuts.